1. Field of the Invention
The present invention relates to an optical element, a package substrate and a device for optical communication.
2. Discussion of the Background
In recent years, optical fibers have been drawing attention mainly in the telecommunications field. In particular, in the field of IT (information technology), communication technology using optical fibers has been necessary for the development of high-speed Internet networks.
Then, it has been proposed for such network communication, including the Internet, that optical communication using optical fibers be used for communication between a basic network and terminal devices (personal computers, mobile devices, games and the like) and communication between terminal devices, in addition to communication in a basic network.
As a device for optical communication usable in a terminal devices for an optical transmitter and receiver system of this kind, the present inventors have previously proposed a device for optical communication comprising a package substrate in which an optical path for transmitting an optical signal is formed and an optical element is mounted on one side thereof, and a multilayer printed circuit board having at least an optical waveguide formed thereon (for example, see JP-A 2004-004427).
As an optical element mounted on the device for optical communication of this kind, a light receiving element and a light emitting element have been used.
With regard to the light receiving element, as shown in FIG. 1, a light receiving element 1, in which a light entering portion 2 is provided in the vicinity of the center of one of the main surfaces having a rectangular shape, an n-side electrode 3 is formed at the neighborhood of one side of the main surface, and at the neighborhood of a side on the opposite of the side where the n-side electrode is formed, a connection pad 5 for connection to a p-side electrode 4 is formed, has been disclosed (for example, see JP-A 2002-344002).
That is, in the light receiving element 1, upon taking the one main surface in a plan view, two external electrodes, i.e. an n-side electrode and a p-side electrode are formed in such a manner that the n-side electrode is formed in a first region of two regions formed by equally dividing the planar surface with a center line X, and two of the p-side electrodes are formed in a second region on the other side.
The contents of JP-A 2004-004427 and JP-A 2002-344002 are incorporated herein by reference in their entirety.